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SA450 
Double-sided Minifloppy 
Diskette Storage Drive 




m 





£1 

r 1 



*AShugart 



TABLE OF CONTENTS 



1 .0 Introduction 1 

1 .1 General Description 1 

1 .2 Specification Summary 2 

1 .2.1 Performance Specifications 2 

1 .2.2 Functional Specifications 2 

1 .2.3 Physical Specifications 3 

1 .2.4 Reliability Specifications 3 

2.0 Functional Characteristics 4 

2.1 General Operation 4 

2.2 Read/Write and Control Electronics 4 

2.3 Drive Mechanism 4 

2.4 Positioning Mechanics 4 

2.5 Read/Write Heads 4 

2.6 Recording Formats 4 

3.0 Functional Operations 7 

3.1 Power Sequencing 7 

3.2 Drive Selection 7 

3.3 Motor On 7 

3.4 Track Accessing 7 

3.4.1 Step Out 7 

3.4.2 Step In 8 

3.5 Side Selection 8 

3.6 Read Operation 9 

3.7 Write Operation 10 

3.8 Sequence of Events 12 

4.0 Electrical Interface 13 

4.1 Signal Interface 14 

4.1 .1 Input Lines 14 

4.1.1.1 Input Line Terminations 15 

4.1.1.2 Drive Select 1-4 15 

4.1 .1 .3 Motor On 15 

4.1 .1 .4 Direction Select 16 

4.1.1.5 Step 16 

4.1.1.6 Write Gate 16 

4.1.1.7 Write Data 16 

4.1 .1 .8 Side Select 17 

4.1 .1 .9 In Use (Option) 17 

4.1 .2 Output Lines 17 

4.1.2.1 Track 00 17 

4.1 .2.2 Index/Sector 17 

4.1 .2.3 Read Data 18 

4.1 .2.4 Write Protect 18 

4.2 Power Interface 18 

4.2.1 Frame Ground 19 

5.0 Physical Interface 21 

5.1 J1 /P1 Connector 21 

5.2 J2/P2 Connector 22 

5.3 Frame Grounding 22 



6.0 Drive Physical Specifications 23 

6.1 Mechanical Dimensions 23 

6.2 Mounting 23 

7.0 Recording Format 24 

7.1 General 24 

7.2 Byte 24 

7.3 Formats 25 

7.3.1 Soft Sectored Recording Format 25 

7.3.1 .1 Track Layout 26 

8.0 Operation Procedures 28 

8.1 Minidiskette Loading 28 

8.2 Minidiskette Handling 28 



LIST OF ILLUSTRATIONS 



Figure 1 . SA450 Double Sided Minifloppy Ill 

2. SA450 Functional Diagram 6 

3. Track Access Timing 8 

4. Read Initiate Timing 9 

5. Read Data Timing (FM) 10 

6. FM and MFM Code Comparisons 10 

7. Write Initiate Timing 11 

8. Write Data Timing (FM) 11 

9. General Control and Data Timing Requirements 12 

10. Interface Connections 13 

1 1 . Interface Signal Driver/Receiver 14 

12. Step Timing 16 

1 3. Write Data Timing 17 

14. Index Timing (SA1 54 Media) 17 

15. Index/Sector Timing (SA1 55 Media) 18 

16. Index/Sector Timing (SA1 57 Media) 18 

1 7. Read Data Timing (FM) 19 

18. Interface Connectors-Physical Locations 21 

1 9. J1 Connector Dimensions 22 

20. J2 Connector 22 

21 . SA450 Physical Dimensions 23 

22. Byte (FM Encoding) 24 

23. Data Bytes 24 

24. Recommended Soft Sector Singla Density (FM) (Even Boundaries) 25 

25. MFM Recommended Format - 256 Bytes/1 6 Records Per Track (IBM type) 25 

26. Recommended Hard Sector FM and MFM Formats 27 




FIGURE 1. SA450 DOUBLE SIDED MINIFLOPPY 



III 



1.0 INTRODUCTION 

1.1 General Description 

The SA450 minifloppy Disk Drives are enhanced double-headed versions of the Shugart SA400 minifloppy 
drives. The SA450 provides up to four times the on-line storage capacity, and faster access time, along with 
improved reliability and maintainability. 

SA450 drives read and write in single and double density on standard 5.25 inch diskettes and on both sides 
of two-sided diskettes. The new drives are exactly the same size as the Shugart SA400 and are plug compati- 
ble. 

The compact SA450 minifloppy Disk Drive offers a reliable, low cost, high performance alternative to OEM 
data storage applications where tape cassette units would have been previously considered. 

SA450 minifloppy drives have these standard features: compact size - 3.25" high x 5.75" wide x 8.0" 
deep, and weight of three pounds; lowest heat dissipation of any floppy drive; positive media insertion to 
keep the door from closing on media; DC drive motor with precision servo speed control and integral 
tachometer; unique stepping motor actuator with direct drive spiral cam and ball bearing V-groove positive 
detent; same proprietary glass bonded ferrite/ceramic read/write head as used in Shugart' s large floppy 
drives; internal write protect circuitry; activity light, and solid die cast chassis. 

Typical applications for the Shugart SA450 are word processing systems, entry level micro-processor 
systems, 'intelligent' calculators, program storage, hobby computer systems and other applications where 
low cost entry level random access data storage is a requirement. 

Key Features 

• Same compact size and weight as the 
SA400 - similar to most tape cassette units 

• 440 Kbyte (unformatted) storage capacity 

• SA400 I/O compatibiluy 

• 125/250 Kbits/second transfer rate 

• Single or double density capability 

• Low heat dissipation 

• Positive media insertion to avoid media 
damage 

• DC drive motor (eliminates AC require- 
ments) 

• Proprietary Read/Write head; designed 
and manufactured by Shugart 

• Write protect circuitry 

• Activity light 



1.2 Specification Summary 



1.2.1 Performance Specifications 

Capacity 
(in bytes) 
Unformatted 
Per Disk (40 Track) 
(35 Track) 
Per Surface (40 Track) 
(35 Track) 
Per Track 
Formatted (16 Records/Track) 
Per Disk (40 Track) 
(35 Track) 
Per Track 
Per Sector 
Formatted (10 Records/Track) 
Per Disk (40 Track) 
(35 Track) 
Per Track 
Per Sector 
Formatted (18 Records/Track) 
Per Disk (40 Track) 
(35 Track) 
Per Track 
Per Sector 
Transfer Rate 
Latency (avg.) 
Access Time 
Track to Track 
Average 

(40 Track) 
(35 Track) 
Settling Time 

1.2.2 FUNCTIONAL SPECIFICATIONS 

Rotational Speed 
Recording Density 

(40 Track) 

(35 Track) 
Flux Density 

(40 Track) 

(35 Track) 
Track Density 
Media Requirements 
SA154 (soft sectored) 
SA155 (16 sectors hard sectored) 
SA157 (10 sectors hard sectored) 
Industry standard flexible diskette 
Oxide on 0.003 in. (0.08mm) Mylar 
5.25 in. (133.4mm) square jacket 



Single Density 


Double Density 


(FM) 


(MFM) 


250,000 


500,000 


218,750 


437,500 


125,000 


250,000 


109,375 


218,750 


3,125 


6,250 


163,840 


327,680 


143,360 


286,720 


2,048 


4,096 


128 


256 


204,806 


409,612 


179,200 


358,400 


2560 


5120 


256 


512 


N/A 


N/A 


161,280 


322,560 


2304 


4608 


128 


256 


125 kilobits/sec 


250 kilobits/sec 


100 ms 


100 ms 


20 ms 


20 ms 


275 


275 


241 


241 


15 ms 


15 ms 



300 rpm 

2938 BPI (FM) 
2728 BPI (FM) 

5876 FCI (FM) 

5456 FCI (FM) 

48 tpi 



300 rpm 



5876 BPI 
5456 BPI 



(MFM 
(MFM) 



5876 FCI (MFM) 

5876 FCI (MFM) 

48 tpi 



1.2.3 Physical Specifications 

Environmental Limits 

Ambient Temperature 
Relative Humidity 
Maximum Wet Bulb 

DC Voltage Requirements 
+ 12V±5% @ 1.80AMax. 
+ 5V ± 5% @ .70A Max. 



Operating 



Shipping 



Storage 



10° to 115°F 


-40° to 1 44°F 


-8° to 1 1 7°F 


20 to 80% 


1 to 95% 


1 to 95% 


78°F 


No Condensation 


No Condensation 



Mechanical Dimensions (exclusive of front panel) 

Width = 5.75 in. (146.1mm) 

height = 3.25 in. (82.6mm) 

Depth = 8.0 in. (203.2mm)Nominal 

Weight = 3 lbs. (1 .36KG) Nominal 
Power Dissipation = 1 1 .5 Watts (40BTU/Hr) Continuous (typical) 
7.3 Watts (25BTU/HR) Standby (typical) 

1.2.4 Reliability Specifications 

MTBF: 8000 POH under typical usage 
PM: Not required 
MTTR: 30 minutes 

Error Rates: 
Soft Read Errors: 1 per 1 9 bits read. 
Hard Read Errors: 1 per 10 12 bits read. 
Seek Errors: 1 per 10 seeks. 

Media Life: 

Passes per Track: 3.0 x 10 6 
Insertions: 30,000 + 



2.0 FUNCTIONAL CHARACTERISTICS 

2.1 General Operation 

The SA450 minifloppy Disk Drive consists of read/write and control electronics, drive mechanism, read/write 
head, and precision track positioning mechanism. These components perform the following functions: 

• Interpret and generate control signals. 

• Move read/write heads to the desired track. 

• Read and write data. 

The interface signals and their relationship to the internal functions are shown in Figure 2. 

2.2 Read/Write and Control Electronics 

The electronics are packaged on one PCB which contains: 

• Index Detector Circuits 

• Head Position Actuator Driver 

• Read/Write Amplifier and Transition Detector 

• Write Protect 

• Drive Select Circuit 

• Drive Motor Control 

2.3 Drive Mechanism 

The DC drive motor under servo speed control (using an integral tachometer) rotates the spindle at 300 rpm 
through a belt-drive system. An expandable collet/spindle assembly provides precision media positioning to 
ensure data interchange. A mechanical interlock prevents door closure without proper media insertion, thus 
eliminating media damage. 

2.4 Positioning Mechanics 

The read/write head assembly is accurately positioned through the use of a precision spiral cam. This cam 
has a V-groove with a ball bearing follower which is attached to the head carriage assembly. Precise track 
location is accomplished as the cam is rotated in discrete increments by a stepping motor. 

2.5 Read/Write Heads 

The proprietary heads are a single element ceramic read/write head with straddle erase elements to provide 
erased areas between data tracks. Thus normal interchange tolerances between media and drives will not 
degrade the signal to noise ratio and insures diskette interchangeability. 

The read/write heads are mounted on a carriage which is located on precision carriage ways. The diskette is 
held in a plane perpendicular to the read/write heads by a platen located on the base casting. This precise 
registration assures perfect compliance with the read/write heads. The read/write heads are in direct con- 
tact with the diskette. The head surface has been designed to obtain maximum signal transfer to and from 
the magnetic surface of the diskette with minimum head/diskette wear. 

2.6 Recording Formats 

The format of the data recorded on the diskette is totally a function of the host system, and can be designed 
around the users application to take maximum advantage of the total available bits that can be written on 
any one track. 

For a detailed discussion of the various recording formats refer to Section 7.0. 



0) 



WRITE PROTECT (COM) 



READ DATA 



READ 
LOGIC 



DRIVE SELECT 



WRITE DATA 



WRITE GATE 



WRITE PROTECT 



READ 
HEADO 



READ 
HEAD 1 



SIDE 
SELECT 



WRITE 
LOGIC 



DRIVE SELECT 



STEP 



DIRECTION SELECT 



DRIVE SELECT (4 LINES) 



TRACK 00 



INDEX/SECTOR 



MOTOR ON 



SIDE SELECT 



SIDE 
SELECT 



CONTROL 
LOGIC 



WRITE 
HEADO 



WRITE 
HEAD 1 



WRITE PROTECT (N/C) 



WRITE 

PROTECT 

SWITCH 



ACTIVITY LIGHT 



NDEX/SECTOR 
LED 



STEPPER MOTOR 



TRACK 00 (COM) 



TRACK 00 (N/O) 



MOTOR ON 




STEPPER A 



MOTOR 

DRIVER 



MOTOR CONTROL^ 



TACHOMETER 



STEPPER B 



STEPPER C 



STEPPER D 



INDEX/SECTOR LED 



INDEX/SECTOR DETECTOR 



FIGURE 2. SA450 FUNCTIONAL DIAGRAM 



3.0 FUNCTIONAL OPERATIONS 

3.1 Power Sequencing 

Applying DC power to the SA450 can be done in any sequence; however, during power up, the WRITE GATE 
line must be held inactive or at a high level. This will prevent possible "glitching" of the media. After applica- 
tion of DC power, a 100 ms delay should be introduced before any operation is performed. Also, after power- 
ing on, initial position of the read/write heads with respect to the data tracks on the media is indeterminant. 
In order to assure proper positioning of the read/write heads after power on, a Step Out operation should be 
performed until the Track 00 line becomes active (Recalibrate). 

3.2 Drive Selection 

Drive selection occurs when a drive's DRIVE SELECT line is activated. Only the drive with this line active will 
respond to input lines or gate output lines. 

3.3 Motor On 

In order for the host system to read or write data the DC drive motor must be turned on. This is accomplished 
by activating the line -MOTOR ON. A 0.5 second delay must be introduced after activating this line to allow 
the motor to come up to speed before reading or writing can be accomplished. 

The motor must be turned off by the host system by deactivating the MOTOR ON line. This should be done if 
the drive has not received a new command within two (2) seconds (10 revolutions of diskette) after com- 
pleting the execution of a command. This will insure maximum motor and media life. 

3.4 Track Accessing 

Seeking the read/write heads from one track to another is accomplished by: 

a. Activating DRIVE SELECT line. 

b. Selecting desired direction utilizing DIRECTION SELECT line. 

c. WRITE GATE being inactive. 

d. Pulsing the STEP line. 

Multiple track accessing is accomplished by repeated pulsing of the STEP line until the desired track has 
Deen reached. Each pulse on the STEP line will cause the read/write heads to move one track either in or out 
depending on the DIRECTION SELECT line. Head movement is initiated on the trailing edge of the STEP 
pulse. 

3.4.1 Step Out 

With the DIRECTION SELECT line at a plus logic level (2.4V to 5.25V) a pulse on the STEP line will cause the 
read/write heads to move one track away from the center of the disk. The pulse(s) applied to the STEP line 
must have the timing characteristics shown in Figure 3. 



WRITE GATE 



::r 



■& 



DRIVE SELECT 



DIRECTION SELECT 



STEP 




REVERSE 



• Vs MIN. 
-Vs MIN. 



LTLT 

-1 



-Vs MIN. 



20 MS MIN. 



FIGURE 3. TRACK ACCESS TIMING 

3.4.2 Step In 

With the DIRECTION SELECT line at minus logic level (OV to .4V), a pulse on the STEP line will cause the 
read/write heads to move one track closer to the center of the disk. The pulse(s) applied to the STEP line 
must have the timing characteristics shown in Figure 3. 

3.5 Side Selection 

Head Selection is controlled via the I/O signal line designated SIDE SELECT. A plus logic level on the SIDE 
SELECT line selects the read/write head on the side surface of the diskette. A minus logic level selects the 
side 1 read/write head. When switching from one side to the other. A 200/*s delay is required after SIDE 
SELECT changes state before a read or write operation can be initiated. Figure 4 shows the use of SIDE 
SELECT prior to a read operation. 



DC POWER 



MOTOR ON 



DRIVE SELECT 



STEP 



WRITE GATE 



SIDE SELECT 



VALID READ DATA 



100 MS MIN. 



u 



35 MS MIN. 



T 200^ 



MIN 



-2^s MAX. 



■0.5 SEC MAX. 



ifr 



^V 



-fir 



u 



<H 



•if- 



nruiruu 



100^S MIN. 



inr 



FIGURE 4. READ INITIATE TIMING 

3.6 Read Operation 

Reading data from the SA450 minifloppy drive is accomplished by: 

a. Activating DRIVE SELECT line. 

b. Selecting Head. 

c. WRITE GATE being inactive. 

The timing relationships required to initiate a read sequence are shown in Figure 4. These timing specfica- 
tions are required in order to guarantee that the read/write heads position has stabilized prior to reading. 

The timing of Read Data (FM) is shown in Figure 5. 

The encoding scheme of the recorded data can be either FM or MFM. FM encoding rules specify a clock bit 
at the start of every bit cell (Refer to Figure 6). MFM encoding rules allow clock bits to be omitted from some 
bit cells, with the following prerequisites 

The clock bit is omitted from the current bit cell if either the preceding bit cell or the current bit cell contains 
a data bit. See Figure 6. 



In the above mentioned encoding schemes, clock bits are written at the start of their respective bits cells 
and data bits at the centers of their bit cells. 



± 250 ns 



READ DATA 



u~iru 



8.0/jS 
NOM. 



4.0^s 
NOM. 



4.0^s 
NOM. 



Lru~u 



BIT 
CELLS 



A = LEADING EDGE OF BIT MAY BE ± 800 ns FROM ITS NOMINAL POSITION. 
B = LEADING EDGE OF BIT MAY BE ± 400 ns FROM ITS NOMINAL POSITION 

FIGURE 5. READ DATA TIMING (FM) 



fm nnnnnnn nnn 



J\ n n n 



-! 2F h 



H F h 



/ 



/ 



/ 



/ 



/ 



/ 



/ 



/ 



BIT 
CELLS 



1 


1 


1 





1 











1 



/ 



/ 



/ 



/ 



/ 



/ 



I D D D 
MFM 'JLJLJl 



Jl TLTLJL/^ 



/ 



/ 



/ 



/ 



FIGURE 6. FM AND MFM CODE COMPARISONS 
3.7 Write Operation 

Writing data to the SA450 is accomplished by: 

a. Activating the DRIVE SELECT line. 

b. Selecting Head. 

c. Activating the WRITE GATE line. 

d. Pulsing the WRITE DATA line with the data to be written. 

The timing relationships required to initiate a Write Data sequence are shown in Figure 7. These timing 
specifications are required in order to guarantee that the read/write heads position has stabilized prior to 
writing. 

The timing specifications for the Write Data pulses are shown in Figure 8. 



10 



MOTOR ON 



DRIVE SELECT 



STEP 



WRITE GATE 



WRITE DATA 



SIDE SELECT 



WRITE DATA 



"J* 



H500 NS MIN. 



■IV- 



• 0.5 SEC MIN. 




35 MS MIN 



■it 



J 



• 8.00/.S MAX. 



200/iS MIN. 



innflnnnnru 



-8^s MIN, 



-fj- 



FIGURE 7. WRITE INITIATE TIMING 



y LJ LJ 



ur~Lr~Lr 



200 ns MIN. 
2100 ns MAX. 



-8.00jis±40 ns- 



. 400/iS 
±20 ns 



FIGURE 8. WRITE DATA TIMING (FM) 



Write data encoding can be FM or MFM. The write data should be precompensated 100 ns on all tracks to 
counter the effects bit shift. The direction of compensation required for any given bit in the data stream 
depends on the pattern it forms with nearby bits. 



11 



3.8 Sequence of Events 

The timing diagram shown in Figure 9 shows the necessary sequence of events with associated timing 
restrictions for proper operation. 



POWER ON 



MOTOR ON 



DRIVE SELECT 

VALID TRK. 00 
AND WRT. PROT. 
OUTPUT 



VALID INDEX/ 
SECTOR OUTPUT 



DIRECTION 
SELECT 



STEP 



WRITE GATE 



WRITE DATA 



VALID 
READ DATA 



SIDE 
SELECT 



■100 MS MIN. 



• 500 ns MAX. 



0.5 SEC 
MAX. 



• 500 ns MAX. 



Vs MIN. 
^|lS MIN. 




20 MS 



15 MS 



.500 ns MIN. 
-0.5 SEC MIN. 



•200^s MIN.- 



-1/tsMIN. 



35 MS 

MIN. 



45- 



-if- 



15- 



SS- 



Sf- 



■4> 



1f- 



-8 M s MAX 



if 



yinrnnnru 



35 MS MIN. 



2^s MAX - 

-0.5 SEC MAX. 



inr 



■if- 



8/iS 
•MIN. 



-100aiS MIN. 



\ni 



-200^s MIN. 



ff 

FIGURE 9. GENERAL CONTROL AND DATA TIMING REQUIREMENTS 



12 



4.0 ELECTRICAL INTERFACE 

The interface of the SA450 minidiskette drive can be divided into two categories: 

1 . Signal 

2. Power 

The following sections provide the electrical definition for each line. 
Refer to figure 10 for all interface connections. 



HOST SYSTEM 




DRIVE 






SPARE SIGNAL LINE 


J1 
2 


i 


FLAT RIBBON 
OR TWISTED « 
PAIR 




IN USE ^ 


4 


> 3 
» 5 

> 7 

' 9 
i11 

'13 
'15 

'17 
'19 
'21 
'23 
'25 
'27 

'29 

'31 
'^■^ 




DRIVE SELECT 4 ^ 


6 . 




^INDEX/SECTOR 


8 , 




DRIVE SELECT 1 ^ 


10 , 




DRIVE SELECT 2 ^ 


12 i 




DRIVE SELECT 3 ^ 


14 




MOTOR ON ^ 


— 4 

16 1 




DIRECTION SELECT ^ 


19 , 




STEP >. 


20 




WRITE DATA > 


22 , 




WRITE GATE ^ 


24 . 




^ TRACK 00 


4 

26 


AC 
GND 

TWISTED 
PAIR 


i— < 




^ WRITE PROTECT 


28 




^ READ DATA 


30 




SIDE SELECT ^ 


32 




SPARE SIGNAL LINE 


1 

34 t 




+ 5VDC ^ 


J2 

4 


' 3 
' 2 

F LOGIC 
GND 




+ 12VDC ^ 


( 

1 






i 


LOGIC 
GND 








/777FRAME"= 
GROUND 



FIGURE 10. INTERFACE CONNECTIONS 



13 



4.1 Signal Interface 

The signal interface consists of two categories: 

1. Control 

2. Data Transfer 

All lines in the signal interface are digital in nature and either provide signals to the drive (input), or provide 
signals to the host (output), via interface connector P1/J1. 

4.1.1 Input Lines 

The input signals are of 3 types, those intended to be multiplexed in a multiple drive system, those which will 
perform the multiplexing and those signals which are not multiplexed and affect all the drives in a daisy 
chain system. 

The input signals to be multiplexed are: 

1. DIRECTION SELECT 

2. STEP 

3 WRITE DATA 

4. WRITE GATE 

5. SIDE SELECT 

The input signals which are intended to do the multiplexing are: 

1. DRIVE SELECT 1 

2. DRIVE SELECT 2 

3. DRIVE SELECT 3 

4. DRIVE SELECT 4 

The signals which are not multiplexed are IN USE and MOTOR ON. 

The input lines have the following electrical specifications Refer to Figure 1 1 for the recommended circuit. 

True = Logical zero = Vin ± 0.0V to + 4V @ lin = 40 ma (max) 

False = Logical one = Vin + 2.5V to + 5.25V @ lin = 250/*a (open) 

Input impedance = 150 ohms 



MAX 1 FEET 
RIBBON OR 
TWISTED PAIR 



+ 5V 




7414 



FIGURE 11. INTERFACE SIGNAL DRIVER/RECEIVER 

14 



4.1.1.1 Input Line Terminations 

The SA450 has been provided with the capability of terminating the input lines listed below. 

1 . MOTOR ON 

2. DIRECTION SELECT 

3. STEP 

4. WRITE DATA 

5. WRITE GATE 

6. SIDE SELECT 

These lines are terminated through a 150 ohm resistor pack installed in a dip socket located at IC location 
3D. 

In a single drive system this resistor pack should be kept in place to provide the proper terminations. 

In a multiple drive system (Program Shunt position MX open) only the last drive on the interface is to be ter- 
minated. All other drives on the interface must have the resistor pack removed. External terminations may 
also be used, then the user must provide the terminations beyond the last drive and each of the five lines 
must be terminated to +5VDC through a 150 ohm 1/4 watt resistor. 

4.1.1.2 DRIVE SELECT 1-4 

The SA450 as shipped from the factory is configured to operate in a single drive system. It can be easily 
modified by the user to operate with other drives in a multiplexed multiple drive system. The user can ac- 
tivate the multiplex option by cutting the MX position of the programmable shunt. This will allow the 
multiplexing of the I/O lines. 

In a single drive system with program shunt positions MX shorted and MS shorted, DRIVE SELECT when ac- 
tivated to a logical zero level, will turn the motor on. Since MX is shorted, the I/O lines are always enabled. 

In a multiple drive system (program shunt position MX open) the four input lines (DRIVE SELECT 1 , DRIVE 
SELECT 2, DRIVE SELECT 3 and DRIVE SELECT 4) are provided so that the using system may select which 
drive oh the interface is to be used. In this mode of operation only the drive with its Drive Select line active 
will respond to the input lines and gate the output lines. In addition, the selected drive will turn its motor on if 
the program shunt position MS is shorted. 

4.1.1.3 MOTOR ON 

This input, when activated to a logical zero level, will turn on the drive motor allowing reading or writing on 
the drive. A .0.5 second delay after activating this line must be allowed before reading or writing. This line 
should be deactivated, for maximum motor life, if no commands have been issued to the drives within two 
seconds (10 revolutions of the media) after completion of a previous command. 

As discussed in section 4.1 .1 .2, when program shunt position MS is shorted the motor will turn on when the 
DRIVE SELECT line is activated or if the MOTOR ON line is activated. A user selectable option is available 
where by the motor will turn on only when the MOTOR ON line is activated. This is accomplished by moving 
the program shunt over one position in its socket so position MM is shorted. 



15 



4.1.1.4 Direction Select 

This interface line defines direction of motion the read/write heads will take when the STEP line is pulsed. An 
open circuit or logical one defines the direction as "out" and if a pulse is applied to the STEP line the 
read/write heads will move away from the center of the disk. Conversely, if this input is shorted to ground or 
a logical zero level, the direction of motion is defined as "in" and if a pulse is applied to the STEP line, the 
read/write heads will move towards the center of the disk. 



4.1.1.5 Step 

This interface line is a control signal which causes the read/write heads to move with the direction of motion 
as defined by the DIRECTION SELECT line. This signal must be a logical low going pulse with a minium pulse 
with of 1/ts and then logically high for 15 ms minimum between adjacent pulses. Each subsequent pulse 
must be delayed by 20 ms minimum from the preceeding pulse. 

The access motion is initiated on each logical zero to logical one transition, or the trailing edge of the signal 
pulse. Any change in the DIRECTION SELECT line must be made at least 1 M s before the trailing edge of the 
STEP pulse, the DIRECTION SELECT logic level must be maintained Vs after trailing edge of STEP pulse 
Refer to Figure 12 for these timings. 



^V 



WRITE GATE 



DRIVE SELECT 



DIRECTION SELECT 



500 ns MIN. 



-**- 



REVERSE 



STEP 



Vs MIN. 




Vs MIN. 



FIGURE 12. STEP TIMING 



4.1.1.6 Write Gate 



The active state of this signal, or logical zero, enables Write Data to be written on the diskette. The inactive 
state or logical one, enables the read data logic and stepper logic. Refer to Figure 13 for timings. 



4.1.1.7 Write Data 



This interface line provides the data to be written on the diskette. Each transition from a logical one level to a 
logical zero level, will cause the current through the read/write heads to be reversed thereby writing a data 
bit. This line is enabled by Write Gate being active. Write Data must be inactive during a read operation. A 
Write Data clamp is provided on the PCB at the interface which holds the WRITE DATA line at a logical zero 
whenever Write Gate is inactive. Refer to Figure 13 for timings. 



16 



WRITE DATA 



kl — LJ — LT 



Ld — LJ — LJ~ 



.200 ns MIN. 
2100 ns MAX. 



— 8.00/»s±40 ns— • 
FIGURE 13. WRITE DATA TIMING 



. 400^s 
±20 ns 



4.1.1.8 Side Select 



This signal defines which side of a two-sided diskette is to be written on to or read from. A logical one selects 
the side head. When switching from one side to the other a 200 pS delay is required before a read or write 
operation can be initiated. 

4.1.1.9 In Use (Option) 

Normally, the activity LED on the selected drive will turn on when the corresponding DRIVE SELECT signal is 
active. The IN USE input can alternately activate the LED on all the drives in a daisy chain or separately in a 
radial configuration. 

4.1.2 Output Lines 

The output control lines have the following electrical specifications. 

True = Logical zero = Vout + 0.0V to + 0.4V 
@ lout = 40 ma (max) 

False = Logical one = Vout + 2.5V (open 
collector @ lout = 250/ia max) 

4.1.2.1 Track 00 

The active or logical zero state of this interface signal indicates when the drive's read/write heads are posi- 
tioned at track zero (the outermost track) and the access circuitry is driving current through phase "A" of 
the stepper motor. This signal is at a logical one level, or inactive state, when the drive's read/write heads 
are not at track zero. When the drive's read/write heads are at track zero and an additional step out pulse is 
issued to the drive, a mechanical stop will keep the read/write heads at track zero but the TRACK 00 signal 
will go inactive. This is because the stepper motor will go to phase "C" and not phase "A". One more step 
out pulse will put the stepper motor back into phase "A" and the TRACK 00 signal will go active again. 

4.1.2.2 Index/Sector 

This interface signal is provided by the drive each time an index or sector hole is sensed at the Index/Sector 
photo detector. Normally, this signal is at a logical one level and makes the transition to the logical zero level 
each time a hole is sensed. 

When using SA1 54 media (Soft Sectored), there will be one pulse on this interface signal per revolution of the 
diskette (200 ms). This pulse indicates the physical beginning of a track. Refer to Figure 14 for the timing. 



u 



LT^ 



-200 MS ± 7.2 MS- 



FIGURE 14. INDEX TIMING (SA154 MEDIA) 



17 



When using SA155 or SA157 media (Hard Sectored), there will be 17 or 11 pulses on this interface line per 
revolution (200 ms). To indicate the beginning of a track, once per revolution there is one index transition bet- 
ween 16 or 10 equally spaced sector transitions. The timing for these signals is shown in Figure 15 and 16. 

When using the Index/Sector signal, look for an edge or transition rather than a level for determining its 
status. With no diskette inserted, this signal remains active or at a logical zero level which is an erroneous 
status. 



SECTOR 14 SECTOR 15 SECTOR 16 . SECTOR 1 . SECTOR 2 



■Lr~~iii ltl 



m y 



12.50 MS 6.25 MS .5 MS MIN 
± .325 MS 



k 



~f 



A.775 MS (MAX.] 



12.50 MS 

FIGURE 15. INDEX/SECTOR TIMING (SA155 MEDIA) 



4.1.2.3 Read Data 



SECTOR 9 




SECTOR 1 



SECTOR 1 



SECTOR 2 



±J LJ bJ Ld" 



5 MS MIN. 



20.0 MS 10.0 MS 

± .72 MS ± .35 MS 

FIGURE 16. INDEX/SECTOR TIMING (SA157 MEDIA) 



This interface line provides the "raw data" (clock and data together) as detected by the drive electronics. 
Normally, this signal is a logical one level and becomes a logical zero level for the active state. Refer to 
Figure 17 for the timing and bit shift tolerance within normal media variations. 

4.1.2.4 Write Protect 

This interface signal is provided by the drive to give the user an indication when a Write Protected Diskette is 
installed. The signal is logical zero level when it is protected. Under normal operation, the drive will inhibit 
writing with a protected diskette installed in addition to notifying the interface. 

4.2 Power Interface 

The SA450 requires only DC power for operation. DC power to the drive is provided via P2/J2 located on the 
non-component side of the PCB near the spindle drive motor. The two DC voltages, their specifications and 
their P2/J2 pin designators are outlined in table 1. The specifications outlined on current requirements are 
for one drive. For multiple drive systems the current requirements are a multiple of the maximum current 
times the number of drives in the system. 



18 



± 250 ns 



READ DATA 



WITH 



I i 



8.(Vs 
NOM. 



4.0/^s 
NOM. 



4.0/.S 
NOM. 



A = LEADING EDGE OF BIT MAY BE 
B= LEADING EDGE OF BIT MAY BE 



800 ns FROM ITS NOMINAL POSITION. 
400 ns FROM ITS NOMINAL POSITION. 



FIGURE 17. READ DATA TIMING (FM) 



P2 PIN 


DC VOLTAGE 


TOLERANCE 


CURRENT 


MAX RIPPLE (p to p) 


1 


+12VDC 


+ 0.6VDC 


1 .80 A MAX. 
.90 A TYP 


100 mV max allowable 


2 


+ 12 Return 








3 


+ 5 Return 








4 


+ 5VDC 


± 0.25VDC 


.70A MAX 
50A TYP. 


50 mV max allowable 



TABLE I. DC POWER REQUIREMENTS 



4.2.1 Frame Ground 



It is important that the drive be frame grounded to the host system AC or frame ground. Failure to do so may 
result in drive noise susceptibility. 

*The 1 2V current is composed of 3 components; Diskette Drive Motor Current, Read/Write stepper functions 
on the PCB, and Write Erase Current. In the multiplex mode, the drive motor is turned off when the Drive is 
deselected, but can be turned on by the MOTOR ON interface line. 

Each of these functions has the following contribution to the + 12V current requirements: 

A. PCB Read/Write function and Stepper Motor (Drive "Standby" current) + 12V current is .55A typ. 
.7A max. 

B. Diskette Drive Motor Start + 1 2V current is 1 .0A typ, 1.1 A max. (motor stalled) 

C. Diskette Drive Motor Running + 12V current is .35A typ, 1.1 A max. (motor stalled) 



19 



5.0 PHYSICAL INTERFACE 

The electrical interface between the SA450 and the host system is via two connectors. The first connector, 
J1 , provides the signal interface and the second connector, J2, provides the DC power. 

This section describes the physical connectors used on the drive and recommended connectors to be used 
with them. Refer to Figure 18 for connector locations. 



Drive PCB 




P1 Connector 
Scotchflex P/N 
346M001 or 
Amp P/N 583717-5 



Frame Ground 

Amp P/N 61664-1 J2 

Amp P/N 350211-1 



Frame Connector 
Amp P/N 60972-1 



P2 Connector 

Amp P/N 1-480424-0 



FIGURE 18. INTERFACE CONNECTORS-PHYSICAL LOCATIONS 



5.1 J1/P1 Connector 

Connection to J1 is through a 34 pin PCB edge connector. The dimensions for this connector are shown in 
Figure 19. The pins are numbered 1 through 34 with the even numbered pins on the component side of the 
PCB and the odd numbered pins on the non-component side. Pin 2 is located on the end of the PCB connec- 
tor closest to the corner and is labeled 2. A key slot is provided between pins 4 and 6 for optional connector 
keying. 



21 



KEY SLOT 




063" NOM. (2X) 



BOARD THICKNESS .062 ± .007" 
FIGURE 19. J1 CONNECTOR DIMENSIONS 



5.2 J2/P2 Connector 

The DC power connector, J2, is mounted on the non-component side of the PCB and is located near the spin- 
dle drive motor. J2 is a 4 pin AMP Mate-N-Lok connector P/N 35021 1-1 . The recommended mating connec- 
tor (P2) is AMP P/N 1-480424-0 utilizing AMP pins P/N 61 473-1 . J2, pin 1 , is labeled on the component side of 
the PCB. Wire used should be #18 AWG. Figure 20 illustrates J2 connector as seen on the drive PCB from 
non-component side. 



® ® ® ® 



FIGURE 20. J2 CONNECTOR 



5.3 Frame Grounding 



The SA450 must be frame grounded to the host system to insure proper operation. If the frame of the drive is 
not fastened directly to the frame of the host system with a good AC ground, a wire from the system AC 
frame ground must be connected to the SA450. For this purpose, a faston tab is provided on the drive near 
the motor control PCB where a faston connector can be attached or soldered. The tab is AMP P/N 61664-1 
and its mating connector is AMP P/N 60972-1. 



22 



6.0 DRIVE PHYSICAL SPECIFICATIONS 

This section contains the mechanical dimensions and mounting recommendations for the SA450. 

6.1 Mechanical Dimensions 

Refer to Figure 21 for dimensions of the SA450. 

6.2 Mounting 

As shipped from the factory, the SA450 is capable of being mounted in one of the following positions: 

1 . Top Loading -mounted upright. 

2. Front Loading -mounted vertical with door opening left or right. 

-mounted horizontal with PCB up. DO NOT HORIZONTAL MOUNT WITH PCB 
DOWN. 



Mounting Holes: 4 on bottom, 2 on each 
side #6-32 x .25 DP MIN (8x) (.63) 



.29 : 
(.73 



.04 
10)" 



CO CJ1 



.19 ± .02 
(.48 ± .05) 




8.25 max 
"(20.96) 



5.675 ± .02 
"(14 41 ± .05) / 



1.905 ± .060 
(4.84 ±15) _ 




■3.12 ± 04 (8x)- 
(7.92 ± .10) 



MINI PCB 



.06 ± .01 
(.15 ± .02) 







.834 + .050 (4 X) 




K 


(2.12 ± .13) 










,i 


ii 






| 




cn 




cn 








fc -J 


J» CD 








en" 1 


io °° 








° + 


" + 








+ . 


+ . 








o 


o 








°S 


CD , 








b° 


b ~* 










K> 
























i 




' 


' 




1 














i 


i 




3.25 + .04 
- .02 






(8.25 +.10) 




6° 




^ .05 








N> 










3.38 + .03 

■« - m » 







(8.58 + .08) 
-.02 



ENVELOPE DRAWING 
(cm) 

FIGURE 21. SA450 PHYSICAL DIMENSIONS 



23 



7.0 RECORDING FORMAT 

7.1 General 

The format of the data recorded on the diskette is totally a function of the host system. As discussed in Sec- 
tion 3.6, data can be recorded on the diskette using FM or MFM encoding. In these encoding techniques, 
clock bits are written at the start of their respective bit cells and bits at the centers of their bit cells. 

7.2 Byte 

A Byte, when referring to serial data (being written onto or read from the disk drive), is defined as eight (8) 
consecutive bit cells. The most significant bit cell is defined as bit cell and the least significant bit cell is 
defined as bit cell 7. When reference is made to a specific data bit (i.e., data bit 3), it is with respect to the 
corresponding bit cell (bit cell 3). 

During a write operation, bit cell of each byte is transferred to the disk drive first with bit cell 7 being 
transferred last. Correspondingly, the most significant byte of data is transferred to the disk first and the 
least significant byte is transferred last. 

When data is being read back from the drive, bit cell of each byte will be transferred first with bit cell 7 last. 
As with reading, the most significant byte will be transferred first from the drive to the user. 

Figure 22 illustrates the relationship of the bits within a byte and Figure 23 illustrates the relationship of the 
bytes for read and write data. 



BYTE 



-TLrLTLrLn n ruin. 



CDC 

JTXLTL 



CDC 

J-LTLTI- 





















BIT CELL 


MSB 


BIT CELL 
1 


BIT CELL 
2 


BIT CELL 
3 


BIT CELL 
4 


BIT CELL 
5 


BIT CELL 
6 


BIT CELL 

7 

LSB 


BIT CELL 
8 



































HEXADECIMAL 
















REPRESENTATION OF 


BINARY 














DATA BITS 


REPRESENTATION OF 














CA 


DATA BITS 1 


1 








1 


1 





CLOCK BITS 


CLOCK BITS 1 


1 


1 


1 


1 1 


1 


1 


FF 



FIGURE 22. BYTE (FM ENCODING) 



I BYTE] BYTE 
1 



10 



11 



12 



13 



14 



15 



16 



BYTE 
17 



BIT CELL OF BYTE IS 
FIRST DATA TO BE SENT 
TO THE DRIVE WHEN 
WRITING AND FROM THE 
DRIVE WHEN READING 



BIT CELL 7 OF BYTE 17 IS 
LAST DATA TO BE SENT TO 
THE DRIVE WHEN WRITING 
AND FROM THE DRIVE 
WHEN READING 



FIGURE 23. DATA BYTES 



24 



7.3 Formats 

Tracks may be formatted in numerous ways and is dependent on the using system. The SA450 can use 
either hard or soft sectored formats. 

7.3.1 Soft Sectored Recording Format 

In this format, the using system may record one long record or several smaller records. Each track is started 
by physical index pulse and then each record is preceded by a unique recorded identifier. This type of recor- 
ding is called soft sectoring. Figure 24 illustrates the recommended single density (FM) formats. Figure 25 il- 
lustrates the recommended double density (MFM) formats. 



PHYSICAL 
INDEX 



n 



HEX BYTE 



NUMBER 
OF BYTES 



GAP 

1 



FF 



16 



■ REPEATED FOR EACH RECORD- 



ED FIELD - 



GAP 
SYNC I AM I ID I CRC I 2 



-DATA FIELD - 



WG GAP 
SYNC I AM I DATA I CRC I OFF I 3 



J 



00 



FE 



m s 



FF 



18 RECORDS 

16 RECORDS 

10 RECORDS 

5 RECORDS 

2 RECORDS 

1 RECORDS 



UPDATE WRITE 



00 



SUSER I 1 
DATA HJ 



FF 



FF 



128 

128 

256 

512 

1024 

2048 



GAP 
4 



FF 



11 


85 


26 


101 


19 


69 


70 


54 


499 


5 


- 


1032 



NOTES: 1 Track Number, Head Number. Sector Number, Sector Length. 

2. IBM or Equivalent CRC Generator. 

3. FB for Data or F8 for Deleted Data. 



FIGURE 24. RECOMMENDED SOFT SECTOR SINGLE DENSITY (FM) (EVEN BOUNDARIES) 



PHYSICAL 
INDEX 



1. 



NUMBER 
OF BYTES 



HEX BYTE 



GAP1 



32 



4E 



-ti" 



-REPEATED FOR EACH NEW RECORD- 



■* ID FIELD 

SYNC I AM I ID I CRC 



12 



NOTE NOTE 
00 1 2 



NOTE 
3 



GAP 
2 



22 



4E 



-DATA FIELD- 



SYNC 



AM 



DATA 



CRC 



GAP 
WGOFF I 3 



GAP 

4 



J 12 


4 


256 


2 


1 J 




NOTE 


USER 


NOTE 




I °° 


4 


DATA 


3 


4E J 



54 250 



4E 4E 



UPDATE WRITE 



NOTES: 1 . First three bytes are Hex A1 with missing Clock Transitions between bits 4 and 5. Last byte is 
Hex FE 

2. Track Number, Head Number, Sector Number, Sector Length (Hex 01). 

3. IBM or Equivalent CRC Generator. 

4. Same as Note 1 , except last byte = Hex FB. 

FIGURE 25. MFM RECOMMENDED FORMAT - 256 BYTES/16 RECORDS PER TRACK (IBM TYPE) 



25 



7.3.1.1 Track Layout 

Index is the physical detector indicating one revolution of the media and is used to initiate format operations, 
generate the Ready signal in the storage device, insure one complete revolution of the media has been sear- 
ched, and for a deselect storage device signal after a certain number of revolutions. 

Gap 1-G1 is from the physical index mark to the ID field address mark sync and allows for 

physical index variation, speed variation and interchange between storage devices. 
ID Field-Sync is a fixed number of bytes for Separator synchronization prior to AM. Includes a . 

minimum of two bytes plus worst case Separator sync up requirements. 

ID Pre Address Mark (MFM)-Three bytes of A1 with unique clock bits not written per en- 
code rules. 

ID Address Mark (FM)-is a unique byte to identify the ID field and not written per the en- 
code rules. 

ID Address Mark (MFM)-is one byte of FE and it is written per the encode rules. 

ID-if a four byte address containing track number, head number, record number, and 

record length. 

CRC-is two bytes for cyclic redundacy check. 
Gap 2 Gap from ID CRC to data AM sync and allows for speed variation, oscillator variation and 

erase core clearance of ID CRC bytes prior to write gate turn on for an update write. 
Data Field-Sync is a fixed number of bytes for Separator synchrohiztion prior to the AM. Includes a 

minimum of two bytes plus worst case separator sync up requirements. 

Pre Data Address Mark (MFM)-Three bytes of A1 with unique clock bits not written per the 

encode rules. 

Data Address Mark(FM)-is a unique byte to identify the Data Field and it is not written per 

the encode rules. 

Data Address Mark (MFM)-is one byte of FB or F8 and it is written per the encode rules. 

Data-is the area for user data. 

CRC-is two bytes for cyclic redundancy check. 

WG OFF (Write Gate Off)-is one byte to allow for Write Gate turn off after an update write. 
Gap 3 Gap from WG OFF to next ID AM sync and allows for erase core to clear the Data Field 

CRC bytes, speed and write oscillator variation, read preamplifier recovery time and system 

turn around time to read the following ID Field. 
Gap 4-G4 is the last gap prior to physical index and allows for speed and write oscillator variation 

during a format write and physical index variation. 

7.3.2 Hard Sectored Recording Format 

In this format, the using system may record up to 16 or 10 sectors (records) per track. Each track is started 
by a physical index pulse and each sector is started by a physical sector pulse. This type of recording is call- 
ed hard sectoring. Figure 26 illustrates the hard sectored formats. The SA1 55 or SA157 minidiskette is to be 
used for these formats. All drive tolerances have been taken into account in developing these formats. 



26 



PHYSICAL 


n 
















SECTOR 


r 


FM 


G1 


SYNC 

00 


AM 
FB 


ID 

m 


DATA FIELD 

[H 


CRC 

m 


G2 
FF 




HEX BYTE 


FF 




NUMBER 
OF BYTES 


16 


6 


1 


4 




2 






16 RECORDS 










128 




36 




10 RECORDS 




FF 






256 




25 
AA 




MFM 




OB 


□ 





B 




HEX BYTE 


AA 




NUMBER 
OF BYTES 


16 


6 


1 


4 




2 






16 RECORDS 










256 




101 




10 RECORDS 










512 




79 





UPDATE WRITE I 



NOTES: 1 Track Number, Head Number, Record Number, Record Length 

2. User Data. 

3. Generated by CRC Generator (IBM or Equivalent). 

FIGURE 26. RECOMMENDED HARD SECTOR FM AND MFM FORMATS 



27 



8.0 OPERATION PROCEDURES 

The SA450 was designed for ease of operator use to facilitate a wide range of operator oriented applica- 
tions. The following section is a guide for the handling procedures on the minidiskette and minifloppy drive. 

8.1 Minidiskette Loading 

To load the diskette, open the door on the front panel, insert the diskette with label towards the door handle 
and close handle. A mechanical interlock prevent door closure without proper media insertion, thus 
eliminating media damage. 

8.2 Minidiskette Handling 

To protect the diskette, the same care and handling procedures specified for computer magnetic tape apply. 
These precautionary procedures are as follows: 

1 . Return the diskette to its storage envelope whenever it is removed from drive. 

2. Do not bend or fold the diskette. 

3. Store diskettes not for immediate use in their box. 

4. Keep diskettes away from magnetic fields and from ferromagnetic materials which might become 
magnetized. Strong magnetic fields can distort recorded data on the disk. 

5. Replace storage envelopes when they become worn, cracked or distorted. Envelopes are designed 
to protect the disk. 

6. Place I.D. labels in the correct location, never use them in layers. 

7. Do not write on the plastic jacket with a lead pencil or ball point pen. Use a felt tip pen. 

8. Do not use erasers. 

9. Heat and contamination from a carelessly dropped ash can damage the disk. 

10. Do not expose diskette to heat or sunlight. 



28 




«=a 



® 



Shugart 



Copyright Shugart 

475 Oakmead Parkway Sunnyvale, California 94086 
Telephone: (408) 733-0100 TWX: 910 339 9355 SHUGART SUVL 

39013-1 10/80 PRINTED IN U.S.A.